The land is unique in Solar System For several reasons: it is the only planet with a breathable oxygen atmosphere, it is covered in liquid water and it is the only celestial body (that we know of) that harbors life. However, the often overlooked property that makes our planet special is that it is the only rocky body in the inner solar system with strong magnetic poles, and a compass would be useless on Mars.
But where do these columns come from and what do they do? To answer these questions, let’s start with a trip to the center of our planet.
The Earth’s core is divided into two layers: a solid inner core and an outer core made of molten metal. Both layers consist of a mixture of magnetic iron and nickel, with a few lighter elements, such as oxygen, silicon and sulfur.
The inner core is extremely dense and hot, like a giant glowing marble. But the outer core is liquid, and it revolves around this solid mass with its own convection current. It is this constant convection that generates the Earth’s magnetic field, John TardunoThe geophysicist at the University of Rochester in New York told Live Science.
Related: What if the Earth’s magnetic field disappeared?
When heat from the inner core continuously radiates to the outer core, it meets material cooled by plate tectonic activity. This cycle drives convection, giving rise to the so-called geodynamo, which produces the magnetic field.
Other planets, such as Mars and Venus, do not have magnetic fields, partly because they lack them Tectonic plates. Evidence suggests that these planets may have once existed GeoDynamo is self-sufficient But it disappeared for unknown reasons. Mercury has a weak magnetic field, but it is The force is only 1.1% of the Earth’s force It does little to protect the planet from solar radiation.
As the liquid metal in Earth’s outer core flows, its motion and high iron content make the planet behave like a giant dipole magnet, with one negatively charged pole and one positively charged pole. About 80% of the Earth’s magnetic field is organized in this way, but the remaining 20% is non-dipole; Instead of forming parallel bands of magnetic force, there are certain areas where the field spins and swirls, acting “like weather patterns that are kind of floating,” Tarduno said.
These irregular patterns produce strange spots in the magnetic field, in places such as South Atlantic anomalyIt is a large region of the Atlantic Ocean where the density of the Earth’s magnetosphere is greatly reduced. Researchers think so “Dent” in the magnetic field It arises from unusual tectonic activity beneath Africa. Areas like the South Atlantic Anomaly are fascinating, but also worrying, for several reasons.
“The magnetosphere is like a protective shell.” Joshua FeinbergA geologist specializing in paleomagnetism at the University of Minnesota told Live Science. It helps deflect huge amounts of dangerous solar radiation away from… Land, acts as a planet-wide sunscreen layer. In areas where the magnetosphere is weak, additional doses of radiation seep through, which may contribute to higher rates of skin cancer.
“Another concern is the impact on satellites,” Tarduno said. Bursts of radiation from the sun are called Coronal mass ejection It can destroy satellites and other spacecraft if they are not protected by the Earth’s magnetic field. This could have catastrophic effects on telecommunications, Internet access, and GPS services in areas affected by the anomaly.
The South Atlantic Anomaly may be 11 million years old, according to a 2020 paper published in the journal. With peopleIt may be related to another planetary magnetic field phenomenon: pole reversal.
The history of Earth’s magnetic field is written in ancient lava flows and deep-sea sediments. These types of rock materials are rich in magnetic mineral fragments, such as tiny iron flakes, that orient themselves along magnetic field lines. “Eventually, this original alignment got locked into the sediment, and we got these deep records of how the Earth’s magnetic field was oriented,” Feinberg said.
From these records, scientists know that our planet’s magnetic poles are drifting over time. Currently, the geographic North Pole is about 310 miles (500 km) long. away from the opposite magnetic pole (which is technically magnetic south at the moment). And about every 300,000 years, the poles suddenly flip, reversing the direction of magnetic north and south, according to NASA.
However, the paleomagnetic record shows that the pole has completely flipped It hasn’t happened for about 780,000 years. Some researchers believe this means so We’re about to flip – And the strength of the anomaly in the South Atlantic could indicate that one of them is nearby.
If the poles flipped, Earth’s magnetic field would drop to 20%, perhaps for centuries. Such an event would plunge our current global communications system into chaos. However, other studies suggest so A coup is not imminent.
Either way, Feinberg said, studying our planet’s interior and the paleomagnetic record will help us understand the complex interplay between the magnetosphere and life on Earth — and perhaps help us prepare for future change.